Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
245 PM EDT TUE AUG 7 2012

.SYNOPSIS...
A STATIONARY FRONT WILL CONTINUE TO WEAKEN ACROSS THE AREA TONIGHT.
A COLD FRONT WILL PUSH ACROSS THE AREA FROM THE WEST LATE FRIDAY.
DRY HIGH PRESSURE WILL THEN BUILD BEHIND THE FRONT OVER THE WEEKEND
WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 230 PM EDT...THE GROUND IS BECOMING INCREASINGLY SATURATED
ACROSS PARTS OF THE AREA AS FAIRLY WIDESPREAD 1 TO 2 INCH RAINFALL
AMOUNTS HAVE BEEN OBSERVED IN THE PAST 24 HOURS AT LOCATIONS IN NE
GA...UPSTATE SC...THE SW NC MTNS...AND THE CLT METRO AREA.
FORTUNATELY...PRECIPITATION RATES HAVE NOT BEEN SPECTACULAR THIS
AFTN DUE TO LIMITED INSTABILITY FROM MORNING RAINFALL AND LOW
CLOUDS. CONVECTION IS ALREADY GOING ALONG THE MTN RIDGES...AND
COVERAGE SHOULD INCREASE THROUGHOUT AS DIVERGENCE FROM THE RIGHT
ENTRANCE REGION OF AN UPPER JETLET BUILDS OVER THIS VERY MOIST
AIRMASS. THE UPPER SUPPORT WILL GRADUALLY MIGRATE EAST ACROSS THE
PIEDMONT THROUGH THE EVENING HOURS BEFORE SHIFTING OFF TO THE
COASTAL PLAIN OVERNIGHT THROUGH WED.

THE ANTECEDENT CONDITIONS CONTINUE TO MAKE ISOLATED FLOODING FROM
RUNOFF LOOK MORE LIKELY...BUT WE ARE ONCE AGAIN LEFT WITHOUT A
PRIMARY FOCUS AREA. THE 850 MB CIRCULATION CENTER OVER SRN AL TODAY
SHOULD STAY SUPPRESSED TO OUR S AND CONTRIBUTE LITTLE IN THE WAY OF
MOISTURE INFLUX OR LOW LEVEL UPSLOPE. SINCE THE AREAS OF BEST
FORCING STILL DO NOT LINE UP WITH THE LOWEST FFG GUIDANCE
AREAS...WILL ONCE AGAIN FORGO A FLASH FLOOD WATCH BUT KEEP THE
MENTION IN THE HWO.

SOME GRADUAL DRYING WILL ARRIVE ALOFT FROM THE WEST OVERNIGHT. THIS
COULD PRODUCE SOME LOW CLOUDS AND FOG...ESPECIALLY ACROSS THE MTN
VALLEYS. THE FOG MAY BECOME DENSE AT TIMES. ONCE THE MORNING LOW
CLOUDS/FOG BURN OFF...INSTABILITY SHOULD RAMP UP QUICKLY AS THE
BOUNDARY LAYER REMAINS MOIST AND 850 TO 500 MB LAPSE RATES STEEPEN
QUICKLY FROM THE NW. LESS IN THE WAY OF TRIGGERS WILL BE FOUND ON
WED...BUT WEAK LOW LEVEL CONVERGENCE WILL EXIST AND DELTA THETA E
VALUES AROUND 30 K WED AFTN WILL MAKE FOR A DECENT WET MICROBURST
THREAT WITH ANY CONVECTION. MAX TEMPS WILL REBOUND TO NEAR NORMAL.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 120 PM TUESDAY...DIURNAL CONVECTION SHOULD GRADUALLY DIMINISH
WED EVENING...GIVING WAY TO CLEARING SKIES AND NEAR-NORMAL MIN
TEMPS. BY THURSDAY AFTERNOON...THE ATMOSPHERE SHOULD ONCE AGAIN
BECOME MODERATELY...IF NOT STRONGLY UNSTABLE...ESPECIALLY ACROSS THE
SOUTHEAST ZONES. CONVECTION SHOULD FIRE BY MID-AFTERNOON IN THE
USUAL DIFFERENTIAL HEATING AREAS ALONG THE ESCARPMENT...AND NEAR
REMNANT BOUNDARY/SURFACE TROUGH W/IN INSTABILITY AXIS JUST
EAST/SOUTH OF THE AREA. WEAK SHEAR/FLOW IS EXPECTED TO RESULT IN
LIMITED COVERAGE...SO WE WILL JUST FEATURE A SHOTGUN LOW CHANCE POP
FOR NOW. OWING TO VERY DRY MID-LEVELS/FORECAST DCAPE APPROACHING
1000 J/KG THERE WILL BE A THREAT FOR ISOLATED PULSE SEVERE STORMS.

THURSDAY NIGHT INTO FRIDAY...HEIGHTS BEGIN TO FALL STRONGLY ACROSS
THE OHIO/MID MISS VALLEY...AS AN UNSEASONABLY STRONG AREA OF
VORTICITY DIGS INTO THE MIDWEST. A MOIST WAA REGIME DEVELOPS IN
RESPONSE...SO ISOLATED/WIDELY SCATTERED CONVECTION IS EXPECTED TO
PERSIST THROUGH THURSDAY NIGHT/EARLY FRIDAY. A STRONGLY FORCED COLD
FRONT WILL APPROACH AND BEGIN TO MOVE ACROSS THE AREA BY LATE IN THE
DAY FRIDAY. SPC HAS OUTLOOKED MUCH OF THE CWFA FOR DAY 4...WHICH
SEEMS REASONABLE IN LIGHT OF THE STRONG FORCING AND FORECAST
SOUNDING DEPICTION OF MODERATE CAPE VALUES. HOWEVER...THERE ARE SOME
ARGUMENTS AGAINST ORGANIZED SEVERE WEATHER FOR FRIDAY. ALTHOUGH THE
FLOW ALOFT IS SOMEWHAT STRONG FOR THIS TIME OF YEAR...THE
UNIDIRECTIONAL NATURE OF SHEAR PROFILES IS RESULTING IN A MAGNITUDE
OF ONLY 25 KT (AT BEST). ALSO...THERE MAY BE QUITE A BIT OF
CLOUDINESS AND SHOWER ACTIVITY IN THE MORNING...WHICH MAY MAKE IT
DIFFICULT TO ACHIEVE THE LEVEL OF INSTABILITY DEPICTED IN THE
SOUNDINGS. NEVERTHELESS...IT/S HARD TO BELIEVE THAT WE WON/T ESCAPE
SUCH AN UNSEASONABLY STRONG SYSTEM WITHOUT SEEING AT LEAST SOME
SEVERE WEATHER...SO THE THREAT WILL CONTINUE TO BE MENTIONED IN THE
HWO.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 145 PM TUESDAY...TROUGH AXIS AND COLD FRONT WILL PUSH ACROSS
THE AREA FRIDAY NIGHT INTO EARLY SATURDAY...WITH SOLID CHANCE/LIKELY
POPS LINGERING INTO FRIDAY EVENING. THE GLOBAL MODELS ARE IN DECENT
AGREEMENT IN STALLING THE FRONT SOUTH OF THE CWFA OVER THE
WEEKEND...WITH MUCH DRIER AIR ADVECTING INTO THE AREA. AFTER A
STORMY FRIDAY/FRI NIGHT...THE WEEKEND MAY TURN OUT TO BE QUITE
PLEASANT...WITH TEMPS AVERAGING A LITTLE BELOW NORMAL...AND POPS/
POSSIBLY RH AVERAGING MUCH BELOW NORMAL.

THE MODELS SUGGEST AIR MASS MODIFICATION WILL OCCUR QUICKLY IN THE
WAKE OF THE DEPARTING TROUGH...AS BERMUDA HIGH ALLOWS LOW LEVEL
MOISTURE/INSTABILITY TO RETURN. A MORE TYPICAL SUMMERTIME PATTERN
SHOULD YIELD MORE TYPICAL SUMMERTIME CONDITIONS...WITH ISOLATED TO
WIDELY SCATTERED DIURNAL CONVECTION EXPECTED ON DAYS 6/7. TEMPS WILL
ALSO LIKELY TO CLIMB TO NEAR NORMAL LEVELS BY THIS TIME.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AT KCLT...COOL TEMPERATURES FROM MORNING CLOUDS AND RAINFALL HAVE
INHIBITED CONVECTION IN THE CLT VICINITY THUS FAR THIS AFTN.
HOWEVER...VISIBLE SATELLITE IMAGERY SHOWS SOME THINNING OF THE
CLOUDS SE OF THE TERMINAL...AND LAPS SFC CAPES ARE PICKING UP
RAPIDLY. THERE SHOULD BE ENOUGH FORCING IN THE VERY MOIST AIRMASS
FOR SOLID SHOWER COVERAGE THROUGH THE AFTN AND EARLY EVENING...WITH
TSRA BEST TIMED FROM 21Z TO 01Z. EXPECT MAINLY VFR CIGS EXCEPT UNDER
SHRA/TSRA...BUT WITH A TRANSITION BACK TO RESTRICTIONS DURING THE
OVERNIGHT HOURS. THERE IS CONSIDERABLE CONCERN THAT IFR OR LIFR
FOG/CLOUDS COULD DEVELOP BY DAYBREAK WED...BUT THE MOS HAS LARGELY
BACKED OFF THIS. WILL FEATURE MVFR CONDITIONS AS A COMPROMISE. AFTER
MORNING RESTRICTIONS LIFT AND SCATTER...EXPECT MAINLY LOWER VFR CIGS
WITH CONTINUED LOW CCL HEIGHTS.

ELSEWHERE...SHRA/TSRA COVERAGE IS INCREASING OVER THE MTNS THIS
AFTERNOON AS UPPER JETLET SUPPORT LINES UP OVER THE SRN
APPALACHIANS. MORNING LOW CLOUDS AND RAIN SHOWERS HAVE CURTAILED
INSTABILITY QUITE A BIT OVER THE FOOTHILLS AND PIEDMONT...BUT THESE
AREAS ARE STARTING TO RECOVER AS WELL AS TEMPS RISE INTO THE LOWER
80S THERE. WILL FEATURE TEMPO TSRA FIRST AT KAVL STARTING AT
19Z...THEN AT THE FOOTHILL SITES BY 21Z. EXPECT MAINLY VFR
CIGS...BUT WITH TEMPO MVFR THROUGHOUT. RESTRICTIONS WILL INCREASE
THIS EVENING THROUGH THE OVERNIGHT HOURS AS SOME DRYING WORKS IN
ALOFT OVER A VERY MOIST BOUNDARY LAYER. EXPECT A TRANSITION THROUGH
MVFR TO IFR OR LOWER DURING THE EARLY MORNING HOURS WED. SLOW
RECOVERY IS EXPECTED WITH MIXING/SCATTERING THROUGH WED MORNING WITH
ALL LOCATIONS VFR BY 15Z TO 16Z WED.

OUTLOOK...A RETURN TO A MORE NORMAL SUMMERTIME DIURNAL TSTM PATTERN
IS EXPECTED ON WED AND THU. A COLD FRONT WILL APPROACH FROM THE NW ON
FRI TO INCREASE THUNDERSTORM COVERAGE THROUGH FRI NIGHT. DRIER HIGH
PRES WILL RETURN OVER THE WEEKEND.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

SYNOPSIS...JDL
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
332 PM EDT TUE AUG 7 2012

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-081945-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-ALEXANDER-
IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-CATAWBA-
ROWAN-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-
MCDOWELL MOUNTAINS-EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-
GREATER RUTHERFORD-POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
332 PM EDT TUE AUG 7 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP OVER
THE AREA THROUGH THIS EVENING. THESE THUNDERSTORMS WILL PRODUCE
LOCALLY HEAVY RAINFALL. ISOLATED FLASH FLOODING COULD RESULT WHERE
THUNDERSTORMS REPEATEDLY AFFECT THE SAME LOCATION. IN ADDITION...
CLOUD TO GROUND LIGHTNING STRIKES AND BRIEF GUSTY WINDS MAY
ACCOMPANY SOME OF THE STORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

A COLD FRONT IS EXPECTED TO APPROACH THE REGION FRIDAY INTO FRIDAY
NIGHT. STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE ASSOCIATED
WITH THE FRONT...WITH THE MAIN THREAT BEING DAMAGING WIND GUSTS.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF DAMAGING
WINDS OR FLASH FLOODING TO OUR OFFICE.

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
434 PM EDT TUE AUG 7 2012

SCZ011-019-072115-
ABBEVILLE-GREENWOOD-
434 PM EDT TUE AUG 7 2012

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN ABBEVILLE AND
WESTERN GREENWOOD COUNTIES THROUGH 515 PM EDT...

AT 429 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES WEST OF VERDERY...OR 6 MILES SOUTHEAST OF
ABBEVILLE. THIS STORM WAS NEARLY STATIONARY.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO VERDERY...
  GREENWOOD AND ABBEVILLE.

SMALL HAIL...WIND GUSTS OF 40 TO 50 MPH AND TORRENTIAL RAIN ARE
EXPECTED WITH THIS STORM.

LAT...LON 3403 8233 3406 8234 3405 8237 3408 8245
      3431 8235 3420 8209 3400 8225

07